fusely from the lachrymal gland. So, if we apply a sapid, or pungent, or acrid substance to the tongue, the mucus of the mouth and salivary glands gushes forth abundantly. That this rapid secretion is usually given out from the vessels under the sympathetic excitement of their nerves-intense "innervation," as some phrase it-I will not deny, but I conceive that this is not the essential or exclusive mode. The immediate efficiency of certain agents seems to me directed at once upon the secretory surface and vessels. It is not true that those acrids most sensibly felt by the delicate nerves of the tongue bring on the greatest mucous discharge from the mouth. Many things increase the quantity, and alter the composition or quality of the intestinal secretions and excretions, without affecting notably the sensibility of their extensive mucous surface. The secretions of all irritated parts are apt to become vitiated and assume morbid qualities, although there may be no apparent change in the structure or permanent condition of the parts. The results, differing with the modes of action upon which they depend, develop specific and characteristic peculiarities in many known cases. The saliva of a hydrophobic animal thus becomes virulently, nay, fatally, poisonous; and cases are related by authors of high estimation in which analogous qualities were exhibited in the saliva of men provoked to vehement and malicious rage, whose bite proved mortal.

CONGESTION.-It is an old maxim in pathology, though perhaps admitting of some dispute whether it be correctly true as the statement of an uniform fact-"ubi irritatio ibi fluxus"-that determination of blood ensues necessarily upon irritation of any part.

"Determination of Blood" admits of explanation in three modes. The first I will call passive or revulsive, as being the effect of causes acting upon some distant part; as when blood expelled from the surface by cold, &c., is driven upon the internal viscera, whose vessels are thus distended. The second exists when the arteries supplying a part, becoming rigid by the undue excitement of their contractile force, give the current passing through them-so Arnott points out-an increased impulse. A leaden tube requires less vis a tergo to conduct a stream of fluid to a given point than a leather one; and with the same will send it farther or more forcibly. In the third, the part itself, the tis sue or organ, may assume or be impressed with greater affinity-chemical or vital, or chemico-vital-for the blood, and may solicit, or become capable of receiving, either to transmit or to retain, a greater quantity. "I infer," says Prof. Draper "that the nervous system has the power of throwing organized atoms into the active and passive state; that this is the fundamental fact upon which all the laws of interstitial death. depend, and upon this principle-namely, its existing allotropic condition, an organized molecule either submits to the oxydizing influ ence of arterial blood, or successfully resists that action." It is by reason of their being in this active allotropic state that the effete particles of tissues are prone to seize oxygen from the blood. We are accustomed, he says, to refer all such phenomena to the influence of the vital force; but what do we know of this power? The phrase is an

empty one. Inflammation he regards as oxydation. The circulation depends on the (chemical) relations of the tissues to the blood. In inflammation there has been that allotropic change in the soft solids involved, that they have assumed a disposition for rapid oxydation-they are active; their relation with arterial blood has become exalted, and the blood flows to the affected part with energy; redness of the part and a higher temperature are the result. Oxydation goes on with promptness; and urea and sulphuric acid begin to accumulate in the urine. But in congestion, it is the reverse: the parts are then thrown into a more passive state; oxydation goes on reluctantly; the amount of tissue metamorphosed diminishes; and the quantity of urea and sulphuric acid in the urine is lessened.

Prick with a needle any point of the skin; lay for an instant the finest hair upon the surface of the eye; let a drop of vinegar fall upon the tongue, the smaller vessels immediately near become promptly distended with red blood, which their natural elasticity enables them to get rid of more or less readily, either by ordinary circulation, or by secretion or effusion. This is one of the modes of congestion which may be termed active, as implying a spontaneous dilatation of the vessels themselves by their own local, independent, vital action, under an impression directed upon their nerves or the nervous filaments in their immediate vicinity.

The passive form of congestion seems to be unconnected with any local irritation whatever; resulting, as far as we can explain it, sympathetically or revulsively from influences applied and acting upon remote organs and tissues. In ague, the cold stage of fever, under long protracted exposure to cold, and in many instances of what we call collapse, a cutaneous capillary paralysis, the fluids desert the external surface, and must be collected in the vessels of the internal organs and tissues. The spleen especially and most frequently, but the brain also, the liver and the lung, may be thus engorged with blood. Hence arise hemorrhages, hypertrophies analogous and heterologous, indurations, various degeneracies, and among the most familiar consequences, inflammation-a subject which we now proceed to discuss in detail.

The changes which constitute INFLAMMATION have been made to undergo the closest, most rigid and attentive examination. The observers differ from each other somewhat, both in regard to the alleged facts and the succession in which they present themselves. The minutest order of vessels, which we denominate capillary, has been most patiently watched, and with the most powerful microscopes, in order to detect the character and course of inflammatory movements excited for the purpose of experiment. The whole history of this capillary system must be confessed to be still, as in the days of Bichat, veiled in the most impenetrable obscurity. Dr. Marshall Hall describes the capillaries as a network of pellucid vessels differing from small arteries in this, that they subdivide without becoming smaller, and anastomose very freely. Forming an intermediate communication between arteries and veins, he regards them as rather passive than active canals, through which the blood is circulated by the vis a tergo, the impulse of the heart and larger arteries, the absorbing action of

the veins, and capillary attraction. Crawford and others attribute an active circulating power to the capillaries as well as to the small arteries, and Parry denies all such power to both sets of vessels. Now, while our knowledge of the natural and healthy functions of the vascular system is so vague and unsettled, we cannot hope to ascertain clearly their diseased operations. During the several stages of the reported experiments upon the transparent parts of animals, the foot of the frog, the ear of the rabbit, etc., the most contrasted phenomena offer themselves to view. At one moment the parts are pale, at another red; at one moment the fluids pass rapidly along the vessel, at another they seem almost stagnant. How shall we decide when inflammation has begun; how determine the cause of the retarded, and the cause of the accelerated circulation? Kaltenbrunner, and after him Crawford, pretend to lay down nice and definite lines of distinction. They arrange the morbid changes under three periods, to which they affix the following titles and descriptions: 1. A period of incubation, of which they themselves remark, "that it is variable in its signs and duration." 2. A period of congestion, which they subdivide into two periods, the first characterized by an increased activity of the vessels, and influx of blood," the second "by a labored slow circulation, arising from overdistension of the vessels and increased thickness and viscidity of the blood." 3. The period of inflammation: "Now the circulation is completely interrupted; the blood coagulates, clogs the vessels, and stagnates in several points of the inflamed part, etc. etc." Crawford further declares that "congestion and inflammation pass so gradually into one another, that they are always necessarily combined; and it may often be extremely difficult to draw a line of demarcation between them."

The obvious truth in the above statement seems to me to be this: that the congestion, both active and passive, of what they designate as the second period, and the complete interruption to circulation in the third, are mere consequences or results of the undefined changes of action and condition which have occurred during what they are pleased to call the stage or period of incubation, these earlier elements in the connected series of phenomena being confessedly too obscure and variable to allow of description.

Addison states that "the accumulation of the colorless cells of the blood, in irritated and inflamed textures, is an established fact;" the globules move irregularly, slowly oscillate to and fro, become stationary, and actually retrograde very often. Houston, having remarked upon the comparatively slow motion of the white globules in the healthy circulation, which, as he says, "lag slowly on, stealing along the sides of the vessels, while the smaller red ones glide easily in the centre of the stream," goes on in these words: "Under inflammation, this tendency to linger is increased. The white globules accumulate in the capillaries and stop up the stream, so that the mass of blood actually stagnates there; hence the rubor, calor, dolor. Whether this stoppage is mechanical, or from want of tone in the blood vessels, or from increased disposition to attraction between them and the globules, is doubtful."

Andral, one of the greatest names which modern medicine can boast, dwells upon the extreme difficulty of properly comprehending the subject of inflammation, and proposes to lessen this difficulty, and to remedy the confusion which has embarrassed the inquiry, by a total abandonment of the word. He contends that it has been employed to express too wide a meaning, and urges the study of its elements separately and progressively. Yet he classes inflammations and congestions together under one head, fixing the attention emphatically or exclusively upon the single condition of hyperæmia-excessive presence of blood in the part. But hyperemia is a common symptom of many conditions, both healthy and diseased. It is present in blushing; in venereal and other physiological modes of excitement, as in weeping, and in the flush of anger and of joy; in both passive and active congestions; in hypertrophies, some at least of which may be regarded as distinguishable both from congestion and inflammation; and in the uterus, first before menstruation and during pregnancy.

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Prof. Bennett, of Edinburgh, maintains that "Inflammation is an exudation of the normal liquor sanguinis." In another place he says tersely: "For all scientific and practical purposes the expression 'exudation' may be substituted for that of 'inflammation.'" His error is important, as leading to an injurious therapeutic. Elsewhere he tells us, "it is a change in a part characterized by the exudation of lymph through the walls of the minute vessels, resulting from changes in the nervous, vascular, sanguineous and parenchymatous elements of that part. These changes, as we are enabled to follow them in the transparent parts of animals under the microscope, are seen to occur in the following order: 1st. The capillary vessels are narrowed, and the blood flows through them with greater rapidity. 2d. The same vessels become enlarged, and the current of blood is slower, although even. 3d. The flow of blood becomes irregular. 4th. All motion of the blood ceases, and the vessel appears fully distended. 5th and lastly, the liquor sanguinis is exuded through the walls of the vessel, sometimes accompanied with extravasation of blood-corpuscles, owing to rupture of capillaries." Now, in reading this clear description, we find nothing to enable us to understand why Prof. B. confines the term "inflammation" to the last step in a process of which indeed it is nothing more than the ultimate consequence or termination.

In the centre of the part inflamed, "in the focus," Paget says, "is stagnation; close around it, congestion, i. e., fulness and slow movement; more distantly, determination, i. e., fulness and rapid movement of blood." These points of stagnation--not coagulation, it must be remembered are regarded by many modern pathologists as the characteristic or pathognomonic features of inflammation.

I am not prepared to give an unqualified assent to any one of the numerous theories of inflammation. Let us for a moment reflect upon the difficulty of constructing any hypothesis which shall explain or consist with all the observed facts, as they are not only differently described by the authorities, but acknowledged by all to vary during the several stages of the process. The circulation is at one time slower, at another more rapid! What state of the affected vessels will account

for these opposite conditions? If we attribute the afflux of blood to spontaneous dilatation of the vessels (as Hunter did), we shall find it difficult to explain the slowness and ultimate stagnation of the blood described by the microscopic observers, in arteries and veins, whose powers of action are heightened, and whose functions performed with greater vigor. If, on the contrary, we regard the vessels (with Thomson) as weakened and debilitated, we shall be embarrassed to account for the accelerated circulation of the early periods, the lively sensibility, the florid redness so quickly restored after the surface has been made pale by pressure. Thomson affirms the velocity of the blood to be sometimes increased and sometimes diminished. common vascular condition may serve as the cause of these contrasted states? Parry refers all the symptoms to an increased momentum of the blood in the part affected; but this he does not ascribe to any satisfactory cause, and has thus removed the difficulty but one step back.

What

For my own part, I consider every theory insufficient in its own. nature, and untenable, which shall proceed upon the supposition of a mere increase or abatement, enhancement or diminution of action, excitement, power.

Inflammation is a condition essentially morbid, not in degree only, but in its very nature; and this is made equally clear, whether we refer to its consequences, its symptoms, or its causes. These causes, infinitely varied as they are, not only affect the force or intensity of action in the part which they impress, but go mainly to determine the mode which that action shall assume, and the results which it shall produce; an influence which is exerted as well by the exciting, occasional, or accidental causes, in many instances, as it is in all by the predisposing or constitutional.

In the meanwhile, the normal or physiological actions are suppressed, subverted, and substituted by the new and diseased actions, and these may be either more or less forcible than the former. Inflammation, like fever, may be either sthenic or asthenic; an alternative probably determined by the state of the system at the time, which may be either entonic or atonic. Less frequently, perhaps, it may take a local character, from the nature of a cause locally applied.

The condition of the blood in inflammation deserves attention here, as it has been supposed to throw some light on the obscurities of this dark subject. "Not long since," says Andral, in his Hæmatology, "Meckel defined inflammation to be congestion, with a tendency to now production." "The study of the blood," proceeds Andral, "shows the justness of this definition. For what else than a new production is the excess of fibrin which suddenly appears in the blood of a person attacked with pneumonia or erysipelas ?" &c. This excess of fibrin to which ho ascribes the buffy coat of the blood, and many of the phenomona of inflammation-is it the cause or the effect of this condition? It is "the least variable sign," yet still not invariable; for the same authority goes on to say: "Except when it occurs in anæmia, this production uniformly denotes inflammation."

Mockol's definition is farther liable to the obvious objection, that